South Korean stocks opened lower Thursday after hitting a nearly three-year high the previous session, as valuation pressure and concerns of surging COVID-19 cases offset vaccine hopes.

The benchmark Korea Composite Stock Price Index (KOSPI) fell 12.41 points, or 0.49 percent, to 2,533.23 in the first 15 minutes of trading.

Stocks fell after hitting a 33-month high in the previous session. Investor wariness increased on valuation pressure and rising coronavirus cases.

Market kingpin Samsung Electronics shed 0.62 percent, and No. 2 chipmaker SK hynix lost 0.31 percent.

Leading chemical firm LG Chem added 1.13 percent, and rechargeable battery maker Samsung SDI advanced 0.6 percent.

Pharmaceutical giant Samsung Biologics edged up 0.25 percent, with Celltrion gaining 1.72 percent.

Internet portal giant Naver climbed 0.71 percent, and its rival Kakao moved up 0.68 percent.

Hyundai Motor, the country's largest carmaker, retreated 0.84 percent.

The local currency was trading at 1,110.65 won against the US dollar, down 6.85 won from the previous session's close. (Yonhap)